Combination terminal and fuse holder arrangement for an electrical circuit

ABSTRACT

A combined terminal and fuse holder arrangement utilized in an electrical circuit, such as an open coil heater assembly. The arrangement includes an insulator having passages therethrough. An electrically conductive element positioned within one of the passages includes a contact portion projecting beyond one side of the insulator. A conductive plate located within another of the passages includes a portion which is exposed on the opposite side of the insulator. A fuse is connected between the conductive element and the plate. In the case of an open coil heater assembly, this fuse is of the thermal type. An electrically conductive member to which the circuit is joined engages the exposed plate portion and extends through the insulator. This member is secured to the insulator by fastening means located on the same side of the insulator as the contact portion of the conductive element.

United States Patent [191 Bourner COMBINATION TERMINAL AND FUSE HOLDER ARRANGEMENT FOR AN ELECTRICAL CIRCUIT Howard L. Bourner, Nashville, Tenn.

Pep Industries, Inc., Nashville, Tenn.

Filed: Apr. 5, 1974 Appl. No.: 458,441

Inventor:

Assignee:

References Cited UNITED STATES PATENTS Ammerman et al. 219/532 Ammerman et al. 337/237 May 6, 1975 [57] ABSTRACT A combined terminal and fuse holder arrangement utilized in an electrical circuit, such as an open coil heater assembly. The arrangement includes an insulator having passages therethrough. An electrically conductive element positioned within one of the passages includes a contact portion projecting beyond one side of the insulator. A conductive plate located within another of the passages includes a portion which is exposed on the opposite side of the insulator. A fuse is connected between the conductive element and the plate. In the case of an open coil heater assembly, this fuse is of the thermal type. An electrically conductive member to which the circuit is joined engages the exposed plate portion and extends through the insulator. This member is secured to the insulator by fastening means located on the same side of the insulator as the contact portion of the conductive element.

8 Claims, 8 Drawing Figures COMBINATION TERMINAL AND FUSE HOLDER ARRANGEMENT FOR AN ELECTRICAL CIRCUIT The invention generally relates to an improved construction of a terminal and fuse holder for use in electrical circuitry, such as an open coil heater assembly. In such an environment, fuses frequently require replacement. Various methods have been devised for facilitating the removal of fuses. One such arrangement utilizes separate terminals for supporting the fuse and the heater coil. Such an arrangement is uneconomical and suffers the further shortcoming of occupying considerable space on the base plate of the assembly. Furthermore, this type of system requires a jumper from one terminal to the other. The physical arrangement just described is particularly disadvantageous in a multi-coil heater assembly inasmuch as the proper positioning of control elements, such as relays and temperature responsive devices, is complicated by the existence of a large number of terminals on the base plate.

In an attempt to overcome the disadvantages of the type of system just described, a combined terminal and fuse holder was devised. This construction is the subject of US. Pat. No. 3,800,263, issued on Mar. 26, l974, in the names of George Edward Ammerman and William McFarlane. The patented construction utilizes a single insulator element to support a terminal and a achieved on the side of the insulator remote from the normal position of the circuit element. This is accomfuse. The terminal comprises an arm projectingthrough the insulator, the arm including a contact at one end thereof which is locatedon the side of the base plate remote from the circuit, such as a heater coil, which is to be energized. The other end of the terminal arm, located on the opposite side of the base plate, is joined to one end of a fuse. Theopposite end of the fuse is connected to a projecting portion of a second arm secured to the insulator. This projecting portion of the arm also is adapted to receive a screw which releasably secures an end of the circuit element to the arm. When a fuse is defective it usually is necessary to move the insulator assembly from engagement with the base plate to a position at which the screw is located on the side of the base plate opposite from that at which it is normally positioned. This permits the person servicing the device ready access to the screw thereby allowing the release of the circuit element. However, during movement of the insulator the connection from the screw to the circuit is stretched, and in the case in which the circuit element is a heater coil, this results in the stretching of the coil until such time as it is reattached to a new terminal and fuse holder assembly and the latter is returned to its usual position with respect to the base plate.

With an arrangement of the type just described, simple fuse replacement is achieved. However, the stretching of the circuit element in order to permit fuse replacement may be deleterious to the element. In fact, certain specifications of the Underwriters Laboratories prevent approval of a tested device if there is deformation of a heater coil as a result of stretching.

In order to avoid this possible problem, the present invention was developed, and to the extent that no stretching of the circuit element is requiredto replace a defective fuse, the present invention is an improvement over that set out in US. Pat. No. 3,800,263. Briefly, the invention comprises an arrangement whereby release of the circuit element from the combined terminal and fuse holder assembly can be plished by joining an end of the circuit element to one end of an electrically conductive member which is arranged so that its opposite end projects beyond the side of the insulator remote from the circuit element where it is secured to the insulator. The insulator supports a conductive plate which is in physical contact with the projecting conductive member when the latter is secured to the insulator in operative position. One end of a fuse is secured to this insulator-supported conductive plate, while the opposite end of the fuse is joined to one end of a conductive element which projects through and beyond the insulator to form a power contact, at its opposite end. Consequently, when a defective combined terminal and fuse holder arrangement needs to be replaced, the projecting conductive member attached to the circuit element is merely disconnected from the insulator and the terminal and fuse holder assembly slipped off without there being any stretching of the circuit element. A new unit is substituted for the defective one and upon securing the projecting member to the insulator, the circuit is completed.

The foregoing invention will be described in further detail by reference to the accompanying drawings wherein:

FIG. 1 illustrates a conventional prior art arrangement for interconnecting a fuse and a coil in an open coil heating assembly, the arrangement being of the type in which the entire heating assembly need not be removed from its operative position in order to replace the fuse;

FIG. 2 is a side elevational view of an open coil heating element assembly incorporating the combined terminal and fuse holder assembly of the type set forth in US. Pat. No. 3,800,263;

FIG. 3 illustrates a terminal and fuse supporting arrangement according to the present invention, the arrangement being illustrated disassociated from the insulator;

FIG. 4 is an end view of one side of an insulator element adapted for use with the arrangement shown in FIG. 3;

FIG. 5 is a view of the opposite end of the insulator element shown in FIG. 4;

FIG. 6 is a view in section of the insulator element taken along line 66 of FIG. 4;

FIG. 7 is an isometric view, partially exploded, illustrating the combined terminal and fuse holder assembly according to the invention; and

FIG. 8 is an isometric view from the side opposite that of FIG. 7, the unit being illustrated in assembled condition.

Referringto FIG. 1, there is disclosed a known manner of securing a fuse and a heater coil end in an open coil heater assembly. A plate 10 serves as a base for supporting a pair of terminals having insulators l2 and 14. Insulator 12 is a two-piece construction held together by a screw 16 passing along the axes of the pieces and cooperating with a pair of nuts 18. The heater coil 20 is soldered to the head of screw 16. Insulator 14 is connected to the base plate by means of a screw 22 passing through an ear 24 projecting from the insulator. A pair of contacts 26 and 28 are provided at one end of insulator 14, and arms 30 and 32 project from the opposite end. Contact 26 and arm 30 are in electrical connection as are contact 28 and arm 32. A

fuse 34 bridges arms 30 and 32, and the fuseis electrically joined to coil 20 by a jumper 36 joined between I contact 28 andithescrew 16. The nuts 18 secure the jumper in electrical contact with the screw.

'With the arrangement just described, it is often the practice in replacingthe fuse to discard the entire in- :sulator-fuse assembly (14,34) in: favor of a new one.

vThis constitutes an economical disadvantage for the FIG. -1 arrangement. I

However, more important than the expense of. replacing the several parts in the arrangement of FIG. 1 is the serious disadvantage of their taking up a substantial amountof space on the surface of base plate. 10.

The necessity of two terminals hinders the placement on the base plate of other important components of an open coil heater system such as relays, temperature respons ive'devices, etc. The problem increases as the number of heater coils becomes greater.

' The combined terminal and fuse holder assembly disclosed in U.S. Pat. No. 3,800,263 and shown in FIG. 2

i From the foregoing description it can be appreciated I that the arrangement of FIG. 2 provides ease of replacement of the combined terminal and fuse holder,

but unless access to screw 72 can be achieved on the 'heater side of the base plate 10, the coil must be stretched to permit release of the terminal'and fuse holder assembly to be replaced. As pointed out previi ously, in someapplications such stretching of the coil may deform the coil material sufficiently so as to be detrimental to its physical and electrical characteristics. Therefore, the arrangement of the present invention was developed so as to eliminate stretching of the coil when the combined terminal and fuse holder as- 'sembly is being replaced.

Referring to FIG. 3 the principal electrically conducj tive components of theimproved'combined terminal and fuse holder assembly are shown. These include a' contact element 80 comprising a stamped "piece of ,metal, the stamping having notches along opposite overcomes the shortcomings of the prior art arrangement illustrated in FIG. lqReferring to FIG. 2, there is illustrated base plate 10 and a'support structure generally indicated as'4 for the open coil heater 20. The

support structure, which is fully described in U.S. Pat.

No. 3,641,312 granted on Feb. 8, 1972, forms no part of the present invention. I v

A single terminal is used to support a fuse 34 and the end of heater coil 20. The terminal includes an insulator 42 formed, with a shoulder which abuts the base plate when the insulator is properly positioned 'to partially project through .an aperture in the base plate. The insulator is secured to the base plate by a screw, not shown. v I

The interior of insulator 42 is provided with passages to receive electrically conductive elements. One of sides of the element, A first pair of notches 82define an car 84 which has a counterpart 84 on the opposite 7 side of the element formed by a pair of notches 82'.

Spaced at a distance from ears 84 is a further pair of ears 86 and '86 defined by notches 88 and 88 respectively. The several ears are used to secure the contact element 80 to an insulator as will be described-hereinafter. The contact element 80 includes at one end a projecting portion 90. A fuse 34 is joined by a suitable conductor 92 to the opposite end of the contact element. Conductor 92 is soldered or otherwise fixed to the contact element 80. The fuse 34, at the end opposite that connected to conductor 92, is joined by a conductor 94 to a conductive plate 96, conductor 94 being these elements is an arm 50 which abuts an interior shoulder formed within one of the insulator passages. Arm 50 includes a projection 56 having ears 58 which fuse.34 has its opposite ends attached to arms 50 1an d60, and arm 50 is provided with an aperture to receive a screw .72. The end of the heater coil 20 is bent in'a loop to pass about the body of the screw so that when the latter is tightened, an electrical circuit is completed from contact68, through projection '66, arm60,

'fuse 34 and arm 50 to the heater coi l 20. I

When Zit'is desired toreplace the combined terminal and fuse holderassembly, the means (not shown) for s ecuring'the insulator 42 to base plate 10 is released,

and the insulator is moved from the positionshown in I FIG. 2 so as to displace the screw 72 from the position 1 shown to theopposite side of the plate '10.'When so located, the screw is loosened torelease the coil 20, and a new terminal and fuse holder is substituted, the screw 72 beingtightene'd to secure the coil 20 to the new as-' sembly; :The insulator then is moved into its operative position with respect to the base plate thus relaxing the stretched condition of the coil 20 which occurred when fth e screw 72 was displaced; V v

secured to the plate in the same manner as conductor 92 is. joined to element 80. Oneend of plate 96 is pro- .vided with a pair of projecting arms 98 and 98 which are notched at their "ends to form tabs 100 and 100'. The opposite end of the plate 96 is bent toform a por- 'tion 102 which extends in a plane at right angles to the plane of the remainder of plate 96. The bent portion 102 includes an aperture 104 the purpose of which will be described hereinafter. On opposite sides of the central portion of plate 96 a pair of ears 1'06 and 106' are formed by spaced notches 108 and 108 the tabs and 100' and ears 106 and 106 serving to retain the plate 96 within an insulator as will be described hereinafter. a

' The insulator construction is shown in FIGS. 48.'

This'insulator may be'formed of any suitable ceramic or synthetic material. The insulator, generally indicated as 42, includes a base portion 110 from which projects a cylindrical portion 112. The interior of in'sulator 42 is provided with passages to receive electrically conductive elements. A first passage 114 is formed to provide an internal shoulder 116 within the insulator. Passage l 14'receives the contact element80, the project ing portion 90 of this element extending completely through the passage with the folded ears 82 and 82 en- I gaging the outer surface 1 18 of the insulator and folded ears 86 and 86' engaging shoulder, 116. As a result, the contact element 80'is secured with respectto insulator .42 as can be best appreciated by reference to FIG. 8.

Asecond passage 120 is provided in the insulator 42,

this passage being circular in cross-section'as bestseen .in FIGS. 4 and 5. This passage communicates with a re- 9 cess 122 in the insulator which forms an internal shoulder 124 within the insulator. A pair of additional passages 126 and 126' extend from the shoulder through the remainder of insulator 42. The latterpassages are positioned to'receive the projecting arms v 98.and 98" of the contactplate 96 shown in FIG. 3 while' the folded ears 106 and 106 of plate 96 engage the'shoulder 124. So positioned, and with tabs 100 and 100 folded against the surface 118 of insulator 42, the contact plate 96 is retained in position with respect to the insulator, as shown in FIGS. 7 and 8. So positioned, portion 102 of plate 96 bears against the outer end surface 1 19 of the cylindrical portion 112 of the insulator 42 (FIG. 7) such that the aperture 104 in portion 102 is in alignment with insulator passage 120. 1

Now that the structure of the improved combined terminal and fuse holder assembly has been described, its operative relationship with an electrical circuit will be outlined. In this regard, reference is made to FIGS. 7 and 8 which illustrate an additional conductive member 127 which in the preferred embodiment of the invention takes the form of a screw. The body portion 128 of member 127 has an external diameter slightly less than the diameter of passage 120 through insulator 42. The head 129 of member 127 is of greater diameter than the aperture 104 in the bent portion 102 of contact plate 96. The end of a circuit element 130, such as an open coil heater, is secured to head 129 by suitable means, such as soldering. To connect the heater to the combined terminal and fuse holder assembly, the insulator 42 is slipped onto member 127 such that the body 128 of the member passes completely through the insulator. A suitable lock washer 132 and nut 134 are employed to tighten the element 127 thereby bringing its head 129 into firm engagement with portion 102 of contact plate 96. When so secured, a circuit is completed to circuit element 130 by a path consisting of contact 80, conductor 92, fuse 34, conductor 94, portion 102 of plate 96, and the head portion 129 of member 128. The circuit being thus completed, the insulator 42 may be connected to a base plate (corresponding to plate of FIG. 2) by passing a screw (not shown) through aperture 132 in insulator portion 110 into the base plate.

When it is desired to change the combined terminal and fuse holder assembly, the connection to base plate 10 is released and nut 134 is loosened from member 127. The insulator 42 and its attached electrical elements are slipped off member 127 and a new assembly is substituted and is secured by nut 134. Since the nut is on the same side of the base plate as contact portion 90 of element 80, and inasmuch as member 127 projects beyond insulator surface 118 on the side of a base plate remote from the heating coil, the improved combined terminal and fuse holder assembly can be replaced without stretching the circuit element 130.

While the assembly just described constitutes a preferred embodiment of the invention, it should be appreciated that a number of variations of the inventive concept are possible. For example, instead of conductive member 127 being a screw, the circuit element 130 may be secured to a plate-like element which projects through and beyond the insulator 42 and which is removably secured to a cooperating projection from contact plate 96 at a point spaced from insulator surface 118. A modification of this alternative embodi- 6 aforesaid projection of plate 96 by means of a screw about which the loop is positioned.

What is claimed is:

l. A combined-terminal and fuse holder adapted to project through an aperture of a supporting plate associated with an electrical circuit arrangement, such as an open coil heater assembly, comprising:

an insulator element having a plurality of passages extending therethrough;

a. first electrically conductive element positioned within one of said passagesand having a contact portion extending beyond one side of the insulator element;

a second electrically conductive element positioned within another of said passages;

a-fuse located on the opposite side of said insulator element from the contact portion of said first conductive element, the fuse beingconnected between said first and second conductive elements;

, conductive means joined to said circuit arrangement and projecting through said insulator element; and

means located on said one side of the insulator for removably securing said conductive means in contact with the second conductive element whereby the terminal and fuse holder are separated from the circuit arrangement when the conductive means is disconnected from said second conductive element.

2. A combined terminal and fuse holder as set forth in claim 1, wherein said conductive means includes a screw secured to the circuit arrangement on the said opposite side of the insulator and extending beyond the said one side of the insulator, the securing means comprising a nut threaded onto said screw.

3. A combined terminal and fuse holder as set forth in claim 2, wherein said second conductive element comprises a plate having an extended portion folded to lie along the said opposite side of the insulator element, said extended portion having an aperture therein through which said screw projects, the screw contacting said extended portion when the nut is threaded onto the screw.

4. A combined terminal and fuse holder as set forth in claim 3, further comprising means for retaining said first and second conductive elements within their respective passages, said retaining means for at least one of the conductive elements including fastening means integral with said conductive element and engaging a surface of the insulator element to hold said conductive element in fixed position within its passage with a portion of the conductive element abutting a shoulder defined by the passage internally of said insulator element.

5. In an electrical circuit assembly, a combined terminal and holder for a thermal fuse adapted to project through an aperture of a supporting plate associated with said electrical circuit to removably locate said fuse adjacent to and in thermally operative relationship with said circuit, the combined terminal and fuse holder comprising:

an insulator element adapted to be removably secured to said plate and to project through said aperture, said insulator having a plurality of passages extending therethrough;

a first electrically conductive element positioned within one of said passages and having a contact portion extending beyond one side of the insulator 7 element to permit access thereto from one side of with the second conductive element whereby theterminal and fuse holder are separated from the circuit when the conductive means is disconnected frorn'said second conductive element.

6. In an electrical circuit assembly as set forth in claim 5, said conductive means including a screw se cured to the circuit on the said opposite side of the insulator and extending beyond the said one side of the v 8 insulator, the securing means comprising a nut threaded onto said screw.

7. In an electrical circuit assembly asset forth in claim 6, said second conductive element comprising a plate having an extended portion folded to lie along the said opposite side of the insulator element, said extended portion having an faperture therein through which said screw projects, the screw contacting said extended portion when the nut is threaded onto the screw. v

8. In an electrical circuit assembly as set forth in claim 7, means for retaining's aidfirst and second conductive elements within their respective passages, said retaining means for at least one of the conductive eleinents including fastening means integral with said conductive element and engaging a surface of the insulator element to hold said conductive element in fixed position within its passage with a portion of the conductive element abutting a shoulder defined by the passage internally of said insulator element. 

1. A combined terminal and fuse holder adapted to project through an aperture of a supporting plate associated with an electrical circuit arrangement, such as an open coil heater assembly, comprising: an insulator element having a plurality of passages extending therethrough; a first electrically conductive element positioned within one of said passages and having a contact portion extending beyond one side of the insulator element; a second electrically conductive element positioned within another of said passages; a fuse located on the opposite side of said insulator element from the contact portion of said first conductive element, the fuse being connected between said first and second conductive elements; conductive means joined to said circuit arrangement and projecting through said insulator element; and means located on said one side of the insulator for removably securing said conductive means in contact with the second conductive element whereby the terminal and fuse holder are separated from the circuit arrangement when the conductive means is disconnected from said second conductive element.
 2. A combined terminal and fuse holder as set forth in claim 1, wherein said conductive means includes a screw secured to the circuit arrangement on the said opposite side of the insulator and extending beyond the said one side of the insulator, the securing means comprising a nut threaded onto said screw.
 3. A combined terminal and fuse holder as set forth in claim 2, wherein said second conductive element comprises a plate having an extended portion folded to lie along the said opposite side of the insulator element, said extended portion having an aperture therein through which said screw projects, the screw contacting said extended portion when the nut is threaded onto the screw.
 4. A combined terminal and fuse holder as set forth in claim 3, further comprising means for retaining said first and second conductive elements within their respective passages, said retaining means for at least one of the conductive elements including fastening means integral with said conductive element and engaging a surface of the insulator element to hold said conductive element in fixed position within its passage with a portion of the conductive element abutting a shoulder defined by the passage internally of said insulator element.
 5. In an electrical circuit assembly, a combined terminal and holder for a thermal fuse adapted to project through an aperture of a supporting plate associated with said electrical circuit to removably locate said fuse adjacent to and in thermally operative relationship with said circuit, the combined terminal and fuse holder comprising: an insulator element adapted to be removably secured to said plate and to project through said aperture, said insulator having a plurality of passages extending therethrough; a first electrically conductive element positioned within one of said passages and having a contact portion extending beyond one side of the insulator element to permit access thereto from one side of the plate; a second electrically conductive element positioned within another of said passages and accessible from the opposite side of the plate, said thermal fuse being positioned on the opposite side of the insulator element and connected between said first and second conductive elements; conductive means joined to said electrical circuit and projecting through said insulator element; and means located on said one side of the insulator and accessible from said one side of the plate for removably securing said conductive means in contact with the second conductive element whereby the terminal and fuse holder are separated from the circuit when the conductive means is disconnected from said second conductive element.
 6. In an electrical circuit assembly as set forth in claim 5, said conductive means including a screw secured to the circuit on the said opposite side of the insulator and extending beyond the said one side of the insulator, the securing means comprising a nut threaded onto said screw.
 7. In an electrical circuit assembly as set forth in claim 6, said second conductive element comprising a plate having an extended portion folded to lie along the said opposite side of the insulator element, said extended portion having an aperture therein through which said screw projects, the screw contacting said extended portion when the nut is threaded onto the screw.
 8. In an electrical circuit assembly as set forth in claim 7, means for retaining said first and second conductive elements within their respective passages, said retaining means for at least one of the conductive elements including fastening means integral with said conductive element and engaging a surface of the insulator element to hold said conductive element in fixed position within its passage with a portion of the conductive element abutting a shoulder defined by the passage internally of said insulator Element. 